Color tunable light emitting device

Abstract

A color/color temperature tunable light emitting device comprises: an excitation source (LED) operable to generate light of a first wavelength range and a wavelength converting component comprising a phosphor material which is operable to convert at least a part of the light into light of a second wavelength range. Light emitted by the device comprises the combined light of the first and second wavelength ranges. The wavelength converting component has a wavelength converting property (phosphor material concentration per unit area) that varies spatially. The color of light generated by the source is tunable by relative movement of the wavelength converting component and excitation source such that the light of the first wavelength range is incident on a different part of the wavelength converting component and the generated light comprises different relative proportions of light of the first and second wavelength ranges.

What is claimed is: 
     
       1. A color tunable light emitting device comprising: an array of excitation sources configured to generate excitation radiation having a first wavelength range; wherein the array includes excitation sources arranged in a plurality of concentric circles; an array of discrete wavelength converting components arranged in the concentric circles, each comprising a phosphor material, the phosphor material configured to convert excitation radiation to light having a second wavelength range; wherein the array of wavelength converting components is uniformly movable relative to the array of excitation sources such that the excitation radiation is incident on different regions of the wavelength converting components; wherein the phosphor material in the wavelength converting components has a concentration per unit area that varies spatially such that a variable amount of the excitation radiation is converted; and wherein the light emitted by the device comprises a combination of light from the excitation source and the phosphor material. 
     
     
       2. The color tunable light emitting device of  claim 1 , wherein the wavelength converting component is movable in a plane whose plane normal is parallel to the direction of propagation of the excitation radiation. 
     
     
       3. The color tunable light emitting device of  claim 1 , wherein the wavelength converting component comprises a transparent substrate material and a phosphor material in powder form distributed substantially uniformly throughout the transparent substrate material. 
     
     
       4. The color tunable light emitting device of  claim 3 , wherein the loading ratio by weight of the phosphor material to the transparent substrate material ranges from 5 to 50 percent. 
     
     
       5. The color tunable light emitting device of  claim 3 , wherein the transparent substrate material is selected from the group consisting of an acrylic and a silicone. 
     
     
       6. The color tunable light emitting device of  claim 3 , wherein the phosphor material is selected from the group consisting of a silicate-based phosphor green phosphor, a silicate-based yellow-green phosphor, a silicate-based orange phosphor, an aluminate-based green phosphor, a nitride, a sulfate, an oxy-nitride, and oxy-sulfate, and a garnet material. 
     
     
       7. The color tunable light emitting device of  claim 1 , wherein the excitation source comprises an InGaN/GaN (indium gallium nitride/gallium nitride) based LED chip operable to generate blue light of wavelength 400 to 465 nm.